Organotin compounds are a major class of biocide, with uses ranging from protection against potato blight to anti-fouling components of marine paints. We propose to synthesize, structurally and spectroscopically characterize, and evaluate for biocidal activity, new organotin compounds. We shall synthesize compounds that promise special activity by virtue of functional substituents, e.g. ionophores, ferrocenyl. The synthesis will be using processes well-established in the laboratory of the PI. Polymerbound organotins will be synthesized to modify the rate of tin release, a crucial aspect of the safe use of organotins. Systematic substitutions into known organotin biocides (e.g. Ph3SnC1) will be performed to modify their activity, and computer-based structure/reactivity models will be developed to evaluate activity, and then to design new structural groupings with enhanced activity. Widespread use of organotins results in tin contamination of estuarine and related waters, and the food chain (farm reared fish and molluscs). Since one mode of decomposition of organotins is thought to be photochemical, we shall study the photochemistry of known biocides in soil environments, e.g. encapsulated in clays, where different results maybe observed compared to normal solution photochemistry. Such studies can lead to formulation of new materials with better, safer, biodegradation properties. Since organotins are also reported to be useful as anti-tumor drugs, all systems will be evaluated for such activity along with biocidal properties. Student training will involve chemical and microbiological components, supervised introduction to, and finally self-use of, spectroscopic and analytical techniques such as NMR, HPLC, GC/mass spectroscopy, and general mentoring in safe and ethical biomedical research.